Concrete is a multi-billion dollar industry worldwide, finding application in the construction and repair of buildings, streets, walkways, paving and runways, as but a few examples. Mixing of concrete for all but the very smallest jobs typically includes mixing of dry concrete with water in a drum to form ready mixed concrete. This drum is often part of a concrete truck, and the addition of water to and admixing with the insufficiently wetted concrete—key steps in the concrete preparation process—may occur at a plant or yard, en route to the job site, or at the job site.
Regardless of when or where the water is added to the concrete, if too much water is added to the concrete, that batch of concrete will not meet performance specifications upon curing (strength, impact resistance, durability and slump, e.g.) and may have an unacceptably high propensity for cracking. Indeed, often the highest quality concrete is that mixture which contains the least amount of water that will still result in a mix that can still be readily placed, and which effectively consolidates and cures after placement. Overly wetted concrete therefore should either be further amended with more dry concrete to salvage the batch or discarded instead of used for the intended application. If an excessively wetted mixture is used, and the expensive removal and replacement with properly mixed concrete is not made, structural failure may result. Too high a water to cement ratio (excessive water proportioning) for a given application (which ratios are well-known for a given design load and/or exposure, e.g.) therefore can pose a significant problem, and can result in loss due to additional labor and perhaps excessive amounts of concrete for a job.
Although it may seem an easily avoidable problem, the industry continues to be plagued by the addition of too much water to the concrete in the concrete drum, whether due to distraction, undertaking too many job duties at once, or simple inattention of an individual(s) controlling the water addition operation. There have even been cases where excessive amounts of water have been intentionally added to the concrete in order to ease placement of the mixture. If a valve operable to control the admission of water to insufficiently wetted concrete is left in the open position for too long, too much water is added to the concrete and, as explained, the batch should thereafter be amended with additional “drier” concrete, or more expensive remedial measures (e.g., tear-out and replacement) must be taken.
It should be understood that the term concrete as used herein has a broad definition, mimicking its use in industry. It can refer to an adequately wetted concrete mixture, an insufficiently wetted concrete mixture, or a dry mix, and includes cementitious mixtures that themselves may include aggregate, gravel, fly ash, ground slag, silica fume, fibers and/or sand. The term concrete as used herein includes all types of cementitious material to which water has been or is to be added, including mortar, pervious concrete, flowable fill, ready-mixed concrete and bedding mix.